I have a DSD DAC feeding a BHK preamp then to a BHK 250 amp and out to my Focal 1038be speakers. Today, after no change to the system, the audio started sounding thin and bright.
I have a backup office system. On a hunch, I swapped out the BHK Preamp for my Schitt Freya S preamp. The thinness and brightness were gone. I repeated the swap two more times with the same results.
It seems the problem is isolated to the BHK preamp. The easiest thing to do that would not require sending it in for repairs is to swap tubes. They have about 1,500 hours on them. What I donât know is if thinness and brightness are a symptom when these tubes go south.
Have any of you had a similar experience that was cured by new tubes?
When tubes age, they degrade gradually until they lose detail. Did this happen just today, and to both channels at the same time?
I use nothing but these tubes: Genalex Gold Lion Pair 12AU7 | vivatubes.com
$70.49 a matched pair.
I donât agree that there is one definable âtube soundâ. And I have and love tubes for lots of reasons, not all for the sound.
But may I answer your thought with: Pass Labs.
Thank you. Even though the system suddenly sounding thin and bright is not a symptom other users may have experienced, it does not hurt to have a backup pair of tubes to swap in and help diagnose. PS Audio sells them for $100 and someone suggested another source.
Are you sure the system changed and not your hearing for the day?
This time of year with temp and humidity swings our hearing systems can and do change radically from day to day.
Just a thought. Might be worth confirming again in a few daysâŚbut yeah, swapping tubes is quick and easy. In my experience, stick with the 12AU7-family for least fuss in the BHK pre.
Oddly, that happened with me yesterday. It sounded fine at turn on and I let it play to warm up. Later when I went to listen the bass was way down in level. The mid bass and subs have separate amps both fed from the same output of the BHK Pre and both are down in level.
The tubes have 980 hrs on them and have been fine before this. The previous set had about 1500 hrs and were fine when changed, so I will swap them back in. Iâll post the results later.
Curious. Not the symptom Iâve usually associated with long in the tooth tubes. First off, tube degradation is generally gradual, not something that suddenly occurs. I hear the slow degradation as being an increase in noise, sometimes itâs of the âcorn popâ variety, a general loss of dynamics because of the raised noise floor. Sudden thinness and brightness - canât remember ever encountering that and being able to isolate it to tubes. Were I to encounter this Iâd first suspect the quality of my mains. Then again, Iâve got the luxury of a box overflowing with new stock and NOS 6922s + 12au7s. So if it persisted for, say, a day I admit Iâd be swapping tubes in my BHK pre to find out if that solves the problem.
Well I tried the older tubes (see my post above) and found no difference. However I can adjust levels in the bass crossover and am close to where it was originally.
Before seeing this thread I thought it might be a break in issue with the new PST and I now think it probably is.